1. Field of the Invention
This original invention relates to ultrathin unit layer and built-up multilayer films comprising a polymeric imine comprising repeat units of the formula EQU [CHRCH.dbd.NR'N ]
where R is aromatic, heteroaromatic, aliphatic, olefinic, acetylenic, or a mixture of these, and R' is aromatic, heteroaromatic olefinic, acetylenic, or a mixture of these.
This original invention relates to a process for the polycondensation synthesis of polymeric imines and the deposition onto selected substrates of said synthesized polymeric imines in the forms of unit layers and built-up multilayers.
This original invention relates to polymeric imine unit layer and multilayer films possessing a heretofore unrealized degree of thinness.
2. Definition of Terms
By the phrase "unit layer" is meant the film or monolayer which is formed according to the teachings of this invention when a compound is spread on the water surface such that its thickness is less than 20 nanometers or such that the surface area occupied per molecule is less than the cross sectional area of said molecule or which forms as a result of a subsequent reaction of said film. The phrase "unit layer" also applies to the above unit layer, which is on the subphase surface, after said unit layer is transferred to a substrate. The thickness of a unit layer is less than 20 nanometers. If the molecules in the unit layer each span the thickness of said unit layer, then said unit layer can be called a "monolayer." The film which results from the one-by-one transfer of unit layers onto a substrate such that they become piled in a stack is called a "multilayer."
By the phrase "essentially monomeric" is meant a polyfunctional, reactive compound which can be introduced into the polycondensation, by means of the spreading of a surface film in the case of a polyfunctional aldehyde or a polyfunctional aldehyde precursor, or as a component of the subphase in the case of a polyfunctional amine.
By the phrase "essentially monomeric polyfunctional aldehyde precursor" is meant a compound which is capable of generating an essentially monomeric polyfunctional aldehyde monomer when spread on an appropriate aqueous subphase
The term "polymeric imine" refers to oligomers or polymers possessing the structure, EQU [CHRCH.dbd.NR'N].sub.m
in which R is aromatic, heteroaromatic, aliphatic, olefinic, acetylenic, or a mixture of these, R' is aromatic, heteroaromatic, olefinic, acetylenic, or a mixture of these, and m is greater than or equal to two.
The phrase "polymeric imine" refers to a linear or network chain compound in which at least two repeat units are linked through an imino bond.
3. Prior Art
While polymeric imines, even wholly aromatic polymeric imines, and films made therefrom are known to the art, uniform, well-controlled films of less than 0.1 micrometers in thickness have not been heretofore produced This prior inability to realize such films is due to inherent limitations of the until now state-of-the-art spin coating and vapor deposition processes.
Melt phase and solution phase syntheses of polymeric imines has been known to the art for many years, an early polycondensation synthesis of poly(p-phenylene terephthalaldimine) being that of R. Adams, J. E. Bullock, and W. C. Wilson [Journal of the American Chemical Society, vol. 45, p. 521 (1923)]. Representative examples include the solid state polycondensation of P. W. Morgan [Japan Patent Application 51-138800(1976)] and the m-cresol solution polycondensation of Suematsu [Japan Patent Application 52-124097(1977)]. Polymeric imines are characterized by high melting points and low solubilities [K. Suematsu and J. Takeda, Journal of Synthetic Organic Chemistry, Japan, vol 41, pp. 972-984 (1983)]. Because of these properties, ultrathin films of polymeric imines have been heretofore unobtainable.
Also, while ultrathin unit layers and monolayer polymers are known to the art, heretofore, not only have these been limited to polymers not possessing the imine moiety in the main chain, but also they have been limited to polymers soluble in spreading solvents or which possess pendant long alkyl side chains. The following references are considered representative of the prior art in the area of polymerized monolayers and multilayers: R. Ackermann, et al, Kolloid-Z. Z. Polym., vol. 2249, 1118 (1971), A Cemel, et al, J. Polym. Sci., Pt A-1, Vol. 10, 2061 (1972), M. Puterman, et al., J. Colloid Interface Sci., Vol 47, 705 (1974), R. Ackermann, et al, Makromol. Chem., Vol 175, 699 (1974), A. Dubault, et al, J. Phys. Chem., Vol. 79, 2254 (1975), Banerjee, and J. Lando, Thin Solid Films, Vol. 68, 1 (1980), D. R. Day, and H. Ringsdorf, Makromol. Chem., 180, 1059 (1979), B. Tieke, V. Enkelmann, H. Kapp, G. Lieser, and G. Wegner in "Interfacial Synthesis, Vol. III, Recent Advances," Marcel Dekker: New York, 1981, K. Fukuda, Y. Shibasaki, H. Nakahara, J. Macromol. Sci. - Chem., Vol. A15, 999 (1981), and T. Folda, L. Gross, H. Ringsdorf, Makromol. Chem., Rapid Commun., Vol. 3, 167 (1982).
Amine-aldehyde condensation by grafting an aliphatic aldehyde onto a water-soluble polylysine was proposed by S. J. Valenty [Macromolecules, 11, 1221 (1978)], but the proposed graft polymers were not isolated, and neither substrate-deposited unit layers nor built-up multilayers were obtained. The imino bonds were to occur as side chains on a preformed polymer.
As mentioned above, uniform ultrathin films comprising a polymeric imine which has imino-bonds in the main chain were not heretofore obtained. Ultrathin films comprising a polymer which is not soluble in spreading solvents and which has no long alkyl side chains were also not obtained. Furthermore, unit layer and built-up multilayer films of wholly aromatic polymers have not heretofore been obtained.
The following references, which are referred to for their disclosures at various points in this application, are incorporated herein by reference.
J. Amer. Chem. Soc., 45, 521 (1923) Japanese Patent Provisional Publication No. 138800/76; No. 124097/77. PA1 J. Org. Syn. Chem., Japan, 41, 972 (1983) Kolloid - Z. Z. Polym., 2249, 1118 (1971). PA1 J. Polym. Sci., Pt A-1, 10, 2061 (1972). PA1 J. Colloid Interface Sci., 47, 705 (1974). PA1 Makromol. Chem., 175, 669 (1974). PA1 J. Phys. Chem., 79, 2254 (1975). PA1 Thin Solid Films, 68, 1 (1980). PA1 Makromol. Chem., 180, 1059 (1979). "Interfacial Synthesis, Vol. III, Recent Advances," Marcel Dekker; New York, 1981. PA1 J. Macromol. Sci. - Chem., A15, 999 (1981). PA1 Makromol. Chem., Rapid Commun., 3, 167 (1982). PA1 Macromolecules, 11, 1221 (1221). "Hakumaku (Thin Films)," in "Shin Jikken Kagaku Koza, 18, Kaimen to Colloid (Interfaces and Colloids), " Maruzen; Tokyo, 1975; Chap. 6, pp 439-516. PA1 A. W. Adamson, "Physical Chemistry of Surfaces," 4th ed.; Wiley: New York, 1982; Chap. IV. PA1 G. L. Gaines, Jr., "Insoluble Monolayers at the Air/Water Interface,", Wiley: New York, 1966; Chap. 4. PA1 G. Goldfinger, "Clean Surfaces: Their Preparation and Characterization for Interfacial Studies," Marcel Dekker: New York, 1970. PA1 J. Amer. Chem. Soc., 45, 521 (1923) Japanese Patent Provisional Publication No. 138800/76; No. 124097/77. PA1 J. Org. Syn. Chem., Japan, 41, 972 (1983) Kolloid - Z. Z. Polym., 2249, 1118 (1971). PA1 J. Polym. Sci., Pt A-1, 10, 2061 (1972). PA1 J. Colloid Interface Sci., 47, 705 (1974). PA1 Makromol. Chem., 175, 699 (1974). PA1 J. Phys. Chem., 79, 2254 (1975). PA1 Thin Solid Films, 68, 1 (1980). PA1 Makromol. Chem., 180, 1059 (1979). "Interfacial Synthesis, Vol. III, Recent Advances," Marcel Dekker: new York, 1981. PA1 J. Macromol. Sci, - Chem., A15, 999 (1981). PA1 Makromol. Chem., Rapid Commun., 3, 167 (1982). PA1 Macromolecules, 11, 1221 (1221). "Hakumaku (Thin Films)," in "Shin Jikken Kagaku Koza, 18, Kaimen to Colloid (Interfaces and Colloids)," Maruzen: Tokyo, 1975; Chap. 6, pp 439-516. PA1 A. W. Adamson, "Physical Chemistry of Surfaces," 4th ed.; Wiley: New York, 1982; Chap. IV. PA1 G. L. Gaines, Jr., "Insoluble Monolayers at the Air/Water Interface,"; Wiley: New York, 1966; Chap. 4. PA1 G. Goldfinger, "Clean Surfaces: Their Preparation and Characterization for Interfacial Studies," Marcel Dekker: New York, 1970.